I can't think of any phone that ships without an oleophobic coating and I'm sure the Mate 9 is no exception.
That being said, some coatings are better than others, lasting longer or being more effective at start.
You can buy oleophobic coating kits on Amazon and the like. Check verified purchaser reviews. Also, I've found that Qmadix Liquid Glass is highly resistant to fingerprints and also claims to give an extra layer of 9H hardness to the glass. You can even register after purchase and get a free $100 insurance against breakage. I'm really into the Liquid Glass product and have put it on a few phones, my 2-in-1 screen, watch faces and fitness bands...
Here is the original Liquid Glass:
https://smile.amazon.com/Qmadix-Liq...513608016&sr=8-1&keywords=qmadix+liquid+glass
This one appears to be their "generic label" which sells for less and has no insurance benefit. However, it does say Qmadix on the back of the packaging and I can't tell that it performs any less than the "name brand."
https://smile.amazon.com/gp/product/B072L5RSSS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Here is my Qmadix Liquid Glass review:
https://forums.androidcentral.com/community-reviews/792185-qmadix-liquid-glass-get-naked.html
Good luck.